testosterone

1. (biochemistry, steroids) A steroid hormone that stimulates development of male secondary sexual characteristics, produced mainly in the testes, but also in the ovaries and adrenal cortex.Examples: "Mammalian testes contain almost no testosterone because it is sent out into the body as quickly as it is made."; "The text recounts a 2011 experiment: Researchers tested 136 healthy young men’s testosterone levels, asked them about their political party affiliations, then gave them either a placebo or ten grams of AndroGel one percent, a high-end dose of a common form of testosterone often used in hormone replacement therapies."countableuncountable

2. (figuratively) Manly behavior, often of an aggressive or foolishly reckless nature.Examples: "Mother encouraged James to rely more on intelligence and less on testosterone to deal with the neighbor's son."; "The MPS is a male orientated and misogynistic environment filled with testosterone, notches on bed posts and conquests."countablefigurativelyuncountable